The present invention relates to automatic fastening machines and methods thereof and, more specifically to an apparatus and method for automatic assembly of major subassemblies.
Large transportation vehicles, such as highway trailers, aircraft, and railroad cars typically comprise multiple subassemblies that are fastened together. For example, a highway trailer includes a chassis, a roof, a floor, and a pair of sidewalls. Generally, a trailer's sidewalls are attached to both the floor and roof of the trailer. In the case of a sixty-foot long highway trailer, the load demands and sheer size of the sidewalls, roof, and floor require that the sidewalls be attached to both the roof and floor by rails that provide sufficient structural support to withstand such loads.
To increase a trailer's structural integrity, it is preferable to attach a sidewall to a top and a bottom rail using multiple points of attachment for rivets or screws. In the case of sidewalls that have vertical support posts, extra support and points of connection must be provided to both securely fasten the sidewall, post, and rail together and to ensure that the increased localized weight and stress due to the vertical posts is adequately supported. For example, a sidewall may be connected to a rail by a single line of rivets parallel to the longitudinal axis of the sidewall and appropriately spaced to securely fasten the sidewall and rail together. However, multiple rivets may be required to securely fasten the sidewall, sidewall rails and sidewall post. Additionally, manufacturing tolerances and human error may result in slight variations in the spacing between sidewall posts on each individual trailer.